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This report contains detailed information on the preparation of the reference material as well as on homogeneity and stability investigations of the property of interest, the equivalent particle diameter, and on the analytical methods to determine the additional properties. The values for particle size distribution are based on the results from laser diffraction measurements of 3 different devices with at least 3 replicate measurements of 4 randomly chosen units of the reference material P206.
The BAM-GGR 016 explains the requirements of ADR, RID, ADN and IMDG for management systems for design, manufacturing, testing, documentation, use, maintenance, and inspection of packagings for package designs for the transport of radioactive material not requiring competent authority approval for all designs of exempted packages, packages type IP-1, IP-2, IP-3 and type A.
The present work demonstrates a sustainable approach of using relatively coarser iron ore particles for ironmaking. The motivation is to reduce the energy consumption in the milling of the iron ore by utilizing coarser iron ore particles (+0.05 mm) and to select a suitable binder for improving pellet properties. Iron ore fines in the range of 0.05–0.25 mm was selected and classified into three size ranges. Fluxed iron ore pellets were prepared using lime as a binder for the basicity of 0, 1, and 2. Reduction of these pellets with a packed bed of coal fines was performed in the temperature range of 900–1200 °C for a duration of 30–120 min. The direct reduction kinetics of the iron ore pellets were studied by employing diffusion and chemical reaction control models to the experimental data. The results show that pellets made with coarser iron ore particles have improved reduction behavior and kinetics. The reduction reaction is found to be a mixed control. The activation energy for the reduction reaction varies from 44.3 to 74.76 kJ mol−1 as iron ore particle size decreases from 0.25 to 0.05 mm and basicity increases from 0 to 2.
This report summarizes findings from the first comprehensive study on digitalization in conformity assessment in Africa. The reults are based on data from a survey among conformity assessment bodies (CABs) conducted in 2023. It highlights the digital maturity of the organizations, the motives, benefits and obstacles of digital transformation as well as the actual technology trends.
This study is part of a global project that covers various other countries (see www.qi-fokus.de).
The industrial sintering process used to produce metallic matrix pads has been altered to diminish the amount of copper used. Unfortunately, replacing a large part of the copper with iron seems to have reached a limit. In the high-energy, emergency-type rail braking used in this study, the materials are put to the very limit of their usage capacity, allowing us to observe the evolution of the microstructure and mechanical properties of sintered, metallic matrix pads. After the braking test, their compressive behaviour was assessed using digital image correlation (DIC), and their microstructure with scanning electron microscopy (SEM). The worn material has three flat layers with different microstructures and compressive behaviours. The boom layer seems unmodified. Macroscopic and microscopic cracks run through the intermediate layer (2–15 mm depth). The top layer has stiffened thanks to resolidification of copper. The temperature reaches 1000 °C during the braking test, which also explains the carbon diffusion into iron that result in the weakening of iron–graphite interfaces in the pad. Finally, submicronic particles are detected at many open interfaces of the worn and compressed pad. Associated with the predominant role of graphite particles, this explains the weak compressive behaviour of the pads.
For the safety of prestressed concrete structures, a test of prestressing steel products for hydrogen-induced stress corrosion cracking is mandatory. The current standardized test methods according to DIN EN ISO 15630-3 have proven deficiencies concerning the reproducibility of the results and thus make it difficult to assess the susceptibility clearly. The WIPANO research project funded by BMWK aimed to improve the test method regarding reproducibility and reliability of results. The project created constant and reproducible test conditions by modifying material, electrolyte, and process parameters. This allowed a clear differentiation between good and bad products. As part of the project, a round robin test was initiated to confirm the applicability and reproducibility of the new test method. The new test method was evaluated for its applicability to the prestressing steel product wire. A draft standard with a proposed conformity criterion for these products was submitted to the responsible ISO committee for approval. According to the current feedback from the committee, the draft standard will be included in the informative annex of the testing standard, which could pave the way for mirroring at European and national standardization levels.
Additive manufacturing processes offer extensive advantages for the design freedom of structures through layer-by-layer production. This enables high weight savings as well as the integration of functions such as cooling channels. This technology thus offers great potential to contribute to a sustainable future. The pioneer among these manufacturing processes is the powder bed fusion of metals with laser beams (PBF-LB/M). This process is characterised by high laser scanning speeds and highly localised heat input, which have a strong effect on the microstructure and thus also on the mechanical properties. For example, the austenitic steel 316L exhibits a cellular structure at the subgrain level. This microstructure feature leads to higher yield strengths and comparable ductility to conventionally processed 316L. In addition to the traditional applications of 316L steel in the petrochemical and nuclear industries, this enables new applications such as medical stents or bipolar plates for fuel cells with proton exchange membranes. However, the layer-by-layer production with high scanning speeds and localised heat input induces cooling rates in the order of 106 K.s-1. The large temperature gradients and the shrinkage restraints of each weld bead and layer lead to the development of complex residual stress fields. These reduce the material performance and can even lead to premature failure. Thus, the fatigue properties are severely affected by rapid crack growth or prematurely developing cracks. Furthermore, specimens may warp during PBF-LB/M or immediately when the components are separated from the build plate. Therefore, residual stress is one of the main disadvantages of PBF-LB/M, making it difficult for this technology to be more widely accepted in the industry. Based on the current state of the literature, the procedure for determining residual stress employing diffraction methods, the influence of the component geometry, as well as the inter-layertime (ILT) on residual stress and, lastly, suitable heat treatment strategies for relaxing residual stress in PBF-LB/M/316L, were identified as insufficiently researched areas.
Determining residual stress is a major challenge. X-ray and neutron diffraction are particularly suitable for filigree structures, which can preferably be produced using PBF-LB/M. Here, the microscopic strain of the lattice planes is used to calculate the macroscopic residual stress. These methods are nondestructive and allow the spatial resolution of the bi-axial and tri-axial residual stress. In the present work, in-situ neutron diffraction tensile tests were performed to analyse the micromechanical behaviour of PBF-LB/M/316L. The suitability of the lattice planes for calculating the macroscopic residual stress was investigated. The (311) lattice plane was found to be the best option for determining the macroscopic residual stress in PBF-LB/M/316L. Furthermore, it was shown that the Kröner model can be used to calculate the X-ray diffraction constants despite the texture. Currently, both aspects are common practices in the determination of residual stress. The results presented here support the validity of this approach and increase the confidence in the experimentally determined residual stress, which has a positive effect on the assessment of quality concerning the safety of a component manufactured by PBF-LB/M.
The geometry of a structure manufactured by PBF-LB/M determines the component stiffness and influences the thermal gradients during manufacture and ultimately the residual stress. The effect of smaller or larger dimensions (larger than 10 mm) on the residual stress is rarely considered. To investigate this aspect, representative test specimens with different thicknesses and lengths were produced. Hence, the influence of the geometry i.e., component stiffness on the residual stress was evaluated. The residual stress was determined using X-ray and neutron diffraction. The analysis of the residual stress showed that an increase in thickness leads to overall higher residual stress. In addition, it was shown that increasing the sample dimension leads to smaller residual stress gradients. Above a threshold value of a few millimetres, no significant change in the residual stress was observed.
The ILT is inherent in every PBF-LB/M construction job and influences the thermal gradients during production and thus the residual stress. A change in wall thickness in a geometrically complex structure or a variation in the number of specimens in the construction process leads directly to a change in the ILT. To simulate this, specimens with different ILT were produced. The residual stress was determined by X-ray and neutron diffraction. The use of a short ILT resulted in higher surface residual stress, but lower volume residual stress. Here, the surface residual stress and the residual stress in the volume showed contrary behaviour. This was attributed to the complex heat conduction during the process, as shown by the thermographic measurements.
To avoid distortion of the specimens or real components upon separation from the build plate or during post-processing steps, stress relief annealing is usually performed after the PBF-LB/M process. Based on standards for heat treatment of welded austenitic steels, heat treatments were performed at low (450 °C for four hours) and high (800 °C and 900 °C for one hour) temperatures. The results show that the heat treatment at 450 °C relaxed the residual stress by only 5 %. This low relaxation is due to the stability of the cell structures. The high-temperature heat treatment showed that 900 °C is required to dissolve the cell structure and achieve a relaxation of about 85 %. This result is in good agreement with the standards for stress relief annealing of welded austenitic steels.
The huge atomic heterogeneity of high-entropy materials along with a possibility to unravel the behavior of individual components at the atomic scale suggests a great promise in designing new compositionally complex systems with the desired multi-functionality. Herein, we apply multi-edge X-ray absorption spectroscopy (extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), and X-ray magnetic circular dichroism (XMCD)) to probe the structural, electronic, and magnetic properties of all individual constituents in the single-phase face-centered cubic (fcc)-structured nanocrystalline thin film of Cr20Mn26Fe18Co19Ni17 (at.%) high-entropy alloy on the local scale. The local crystallographic ordering and component-dependent lattice displacements were explored within the reverse Monte Carlo approach applied to EXAFS spectra collected at the K absorption edges of several constituents at room temperature. A homogeneous short-range fcc atomic environment around the absorbers of each type with very similar statistically averaged interatomic distances (2.54–2.55 Å) to their nearest-neighbors and enlarged structural relaxations of Cr atoms were revealed. XANES and XMCD spectra collected at the L2,3 absorption edges of all principal components at low temperature from the oxidized and in situ cleaned surfaces were used to probe the oxidation states, the changes in the electronic structure, and magnetic behavior of all constituents at the surface and in the sub-surface volume of the film. The spin and orbital magnetic moments of Fe, Co, and Ni components were quantitatively evaluated. The presence of magnetic phase transitions and the co-existence of different magnetic phases were uncovered by conventional magnetometry in a broad temperature range.
In our current research project „Reincarnate“ we aim to anchor the idea of the circular economy in the European construction industry and significantly extend the life cycle of buildings, construction products and materials through innovative solutions. On the long term, this is an approach reduce construction waste by 80 percent and the CO2 footprint of the construction sector by 70 percent."
This project has received funding from the European Union’s Horizon Europe research and innovation programme and will take you on a tour on what are the drivers, what is the goal, who are the partners and how we want to make the world a better place!
With 8% of man-made CO2 emissions, cement production is an important driver of the climate crisis. By using alkali-activated binders, part of the energy-intensive clinker production process can be dispensed. However, as numerous raw materials are involved in the manufacturing process here, the complexity of the materials increases by orders of magnitude. Finding a properly balanced binder formulation is like looking for a needle in a haystack. We have shown for the first time that artificial intelligence (AI)-based optimization of alkali-activated binder formulations can significantly accelerate research.
The "Sequential Learning App for Materials Discovery" (SLAMD) aims to accelerate practice transfer. With SLAMD, materials scientists have low-threshold access to AI through interactive and intuitive user interfaces. The value added by AI can be determined directly. For example, the CO2 emissions saved per ton of cement can be determined for each development cycle: the more efficient the AI optimization, the greater the savings.
Our material database already includes more than 120,000 data points of alternative binders and is constantly being expanded with new parameters. We are currently driving the enrichment of the data with a life cycle analysis of the building materials.
Based on a case study we show how intuitive access to AI can drive the adoption of techniques that make a real contribution to the development of resource-efficient and sustainable building materials of the future and make it easy to identify when classical experiments are more efficient.